Sighting in Thaon-les-Vosges, March 24, 2021

A witness reported seeing a coloured point of light low in the night sky on several occasions between 24 and 30 March 2021. They photographed and filmed it on 29 March. The point drifted slightly to the right, changed colour at random, and eventually vanished, for reasons the witness did not understand. During the observation on 30 March, it disappeared at 00:16 local time. The gendarmerie's neighbourhood enquiry found no other witnesses.

Analysis of the account, the features described and the repeated sightings pointed to an astronomical mix-up: the object was Sirius. The witness had been struck by its brightness, which exceeds that of other stars, Sirius being the brightest star visible. The slight shift to the right matches the azimuth drift caused by the Earth's rotation. The gradual drop in height went unnoticed because the witness's horizon was cluttered and they were not perfectly still. At 00:16 on 30 March, Sirius stood 2.5° above the horizon, consistent with an apparent setting, since local terrain hid the true horizon. The colour changes are explained by atmospheric optical effects (diffraction, turbulence, refraction, absorption, scattering), and the non-pointlike shape in the images came from camera distortions, not visible to the naked eye. GEIPAN classified the case as A: mistaken identification of Sirius setting.